This species has only recently been recognised in Britain, previously being confused under the name T. unicolor. Most records of the latter belong to the present species.

Both Tachysphex unicolor and T. nitidus are present in the British Isles. The separation of the two species has not been adequately documented in the English language, but is correct in Bitsch et al., 2001 Faune de France 86. Unless explicitly stated that this key has been used, or any subsequent one which recognises this situation, all records should be placed in agg.

Crossocerus dimidiatus, known under the generic names Crabro, Blepharipus (in error) or Cuphopterus in older works, is one of the larger British Crossocerus with yellow-spotted gasters, resembling Crabro and Ectemnius, rather than the smaller, darker Crossocerus more typical of the British fauna.

Of the several Crossocerus species that nest in the soil, this is the only one with a boldly marked yellow gaster (but beware of specimens without spots). The spine at the bottom of the occipital carina is diagnostic for species recognition.

Hoplisoides punctuosus is known as Gorytes punctatus in some older literature. Hoplisoides has only recently been given generic status by British and some European authorities, as it resembles Gorytes in all but a few details. The genus Hoplisoides is found on all continents except Australia and Antarctica.

Of the 24 species of endangered bees listed in the British Red Data Book (Shirt, 1987), four have only been recorded in recent years from a single site. One of these is Osmia xanthomelana, the largest and perhaps the most attractive of the ten species of British Osmia.

Melitta species generally have very narrow pollen preferences, either visiting a single species (monolectic) or a group of closely related species (oligolectic). The present species belongs to the second category.

This is the only example in Britain of a small 'carpenter bee', so-called because of its nesting habits - the female excavating its nest burrow in dead, pithy stems.

Males of this strikingly-coloured, medium-sized bee hover and dart around patches of flowering labiates (and some other flowers) and regularly pursue other insects.